The present application claims priority to Japanese patent application of Takimoto et al., filed May 21, 2001, No.2001-150478, and Japanese patent application of Takimoto et al., filed May 21, 2001, No.2001-150484, and Japanese patent application of Totani et al., filed May 21, 2001, No.2001-151516, and Japanese patent application of Mizuno et al., filed Dec. 21, 2001, No.2001-390263, and Japanese patent application of Totani et al., filed Jan. 23, 2002, No.2002-14616, the entirely of each is hereby incorporated into the present application by this reference.
The present invention relates to a knee protecting airbag device capable of protecting the knees of a passenger with an airbag, which extends and expands when filled with an inflating gas.
In the prior art, a device for protecting the knees of a passenger is exemplified by an airbag device having a construction, disclosed in Unexamined Published Japanese Patent Application No. 9-123862. This airbag device is arranged at a position below a steering column to protect the knees of a driver. The airbag device comprises an airbag, an inflator for feeding an inflating gas to the airbag, a case for housing the airbag and the inflator, and an airbag cover for covering the housed airbag and for allowing the airbag to protrude. The airbag extends and expands, when activated, toward the lower face of the upper portion of a column cover.
In the airbag device thus constructed, a strong reaction force pushing the case forward is applied to the case when the airbag extends and expands with the inflating gas from the inflator. Therefore, the case has to be mounted and fixed on a highly rigid structural member such as a steering column so that the case is not moved by the reaction.
At positions below the steering column, where the airbag device of the aforementioned construction is located, however, there are usually arranged not only the steering column but also a tilt mechanism, a telescopic mechanism, a parking brake device and so on, thereby leaving just a narrow space for accommodating the airbag device. Therefore, the space for mounting and fixing the case on the steering column is so narrow that the installation requires a long time.
In order to protect the knees of a passenger seated on the front seat next to the driver, or the passenger seat, on the other hand, it is conceivable to arrange the knee protecting airbag device in front of the passenger seat. In front of the passenger seat, where such an airbag device would be installed, however, there are closely arranged a main airbag device , which includes an airbag for extending and expanding between the windshield and the passenger to protect the passenger, the duct of an air conditioner, a, glove box and so on. Therefore, the space for installing this airbag device is narrow as in the case of the driver""s seat, and the space for mounting and fixing the case is narrow.
In the airbag device thus constructed, moreover, it is also conceivable to arrange a case or the like on a plate-shaped holding member such as a knee panel (or a knee bolster) to be arranged in front of the seated passenger.
The knee panel is connected to a movement energy absorber, which is located in front of the knee panel. Such a panel would face a large portion the front side of the seated passenger. The knee panel receives the forward moving knees of the passenger at the time of a front collision of the vehicle and moves forward together with the knees, to deform the kinetic energy absorber in front. In short, the knee panel acts to dampen the shock on the knees of the forward-moving passenger.
When the airbag and the inflator are to be housed in the plate-shaped holding member or knee panel, the airbag cover for covering the folded airbag also has to be mounted on the holding member.
This airbag cover is desirably constructed to widely cover the rear side of the holding member such as the knee panel to avoid degradation in appearance. The airbag cover is desirably formed not separately of but integrally with a door portion, which covers the folded airbag but is opened when pushed by the expanding airbag. In this construction, therefore, the door portion is formed integrally with the rest of the airbag cover by providing a breakaway in its periphery.
When the airbag cover having the integrated door portion is mounted on the aforementioned holding member, however, there arises a problem that the breakaway portion is smoothly broken to open the door portion.
In the airbag device thus constructed, the airbag module, which includes the airbag, the inflator, the case and the airbag cover, is mounted and fixed on the vehicle body by supporting it on a mounting bracket.
When an airbag that has completed its extension and expansion cannot completely absorb the kinetic energy of the knees, the aforementioned mounting bracket of the airbag device is constructed to deform and buckle plastically, to absorb the kinetic energy of the knees.
In short, the airbag device is constructed to absorb the kinetic energy of the knees by buckling the mounting bracket. For this, the mounting bracket has a structure in which it is extended generally forward from the airbag module and is fixed at a predetermined portion of the vehicle body. As a result, the forward extension of the mounting bracket requires space.
If the distance between the airbag module and the portion of the vehicle body for rigidly fixing the module is short, therefore, the structure having the aforementioned mounting bracket is not acceptable, and the conventional device has a low degree of freedom with regard to locating the device.
In addition, if the airbag device of the aforementioned construction is mounted on a vehicle, the distance from the steering column cover or the instrument panel to the knees of the passenger is usually short when the passenger is seated. In the case of the driver, the driver is frequently depressing the brake pedal when the airbag device deploys, so that the distance from the column cover to the driver""s knees is shorter. Therefore, the airbag has to quickly expand in order for it to protect the knees properly.
In addition, if the airbag device of this kind is arranged at the driver""s seat, the steering column, the tilt mechanism, the telescopic mechanism, the parking brake and so on are close to the location of the airbag device. Therefore, it is difficult to provide a large housing space for locating the knee protecting airbag device. Especially in recent years, it has been difficult to make space to accommodate the width of the airbag device in the directions perpendicular to the axis of the case when a glove box or the like is arranged below the column cover. It is, therefore, desired to make the airbag device compact by making the width as small as possible in the directions perpendicular to the case axis.
A first object of the invention is to provide a knee protecting airbag device that can be easily mounted in a vehicle.
A second object of the invention is to provide a knee protecting airbag device, in which a door portion can be pushed and smoothly opened even if an airbag cover having the an integral door portion is mounted on a plate-shaped holding member located in front of the knees of a seated passenger.
A third object of the invention is to provide a knee protecting airbag device that can absorb the kinetic energy of the knees, if not fully absorbed by the airbag, and that can improve the degree of freedom in locating the device.
A fourth object of the invention is to provide a knee protecting airbag device that can extend the airbag quickly enough to protect the knees of the passenger properly.
A fifth object of the invention is to provide a knee protecting airbag device that is reduced in width in the direction perpendicular to the axis of a case so that it can be located in a narrow space.
The first object of the invention can be achieved by a knee protecting airbag device having the following construction.
The knee protecting airbag device comprises a folded airbag, an inflator for feeding an inflating gas to the airbag, and a case housing the airbag and the inflator. The device is arranged in the vehicle in front of a seated passenger. The airbag, when fed with the inflating gas, extends and expands, while protruding backward from the opening of the case, to protect the knees of the passenger. The knee protecting airbag device further comprises a holding member, which has a mounting portion mounted to the vehicle. The holding member includes a communication hole communicating with the opening of the case, for allowing the expanding airbag to protrude, and a support face arranged on the periphery of the communication hole, for supporting the vehicle front side face of the extending and expanding airbag.
In the knee protecting airbag device, the case housing the folded airbag and the inflator is held by the holding member. By using the mounting portion formed at the holding member, the knee protecting airbag device is mounted on the vehicle. At the time of mounting the knee protecting airbag device on the vehicle, therefore, the mounting portion of the holding member holding the case is mounted and fixed on the highly rigid mounting portion of the vehicle body, so that the knee protecting airbag device can be mounted on the vehicle. At this time, the work to mount the mounting portion of the holding member on the mounting portion of the vehicle body can be done in the free space provided both transversely and vertically from the pre-arranged position of the case. By setting the position of the mounting portions of the holding members at a location where the working space can be easily provided, therefore, the work to mount the knee protecting airbag device on the vehicle can be done more easily than when the case is mounted and fixed directly on the mounting portion of the vehicle body.
Of course, the holding member holding the case is mounted on the highly rigid mounting portion of the vehicle body so that the case housing the airbag and the inflator is also held in a stable manner.
In the knee protecting airbag device thus constructed, moreover, the front face of the airbag, when it is extended and expanded, is supported by the support face of the holding member. Even when the airbag interferes with the knees of the passenger when expanded, therefore, the airbag does not move forward but can properly protect the knees of the passenger.
In the knee protecting airbag device thus constructed, therefore, the stable support of the case and the airbag, when extended and expanded, can be provided, and the mounting of the knee protecting airbag device on the vehicle can be facilitated.
In the knee protecting airbag device thus constructed, it is preferred that the case housing the folded airbag and the inflator is assembled in advance with the holding member into one assembly.
With this construction of the knee protecting airbag device, the airbag, the inflator, the case and the holding member can be transported and stored in the assembled state. Therefore, it is easy to handle these members when mounting them on the vehicle.
A second object of the invention can be achieved by a knee protecting airbag device having the following construction.
In a knee protecting airbag device, a knee protecting folded airbag and an inflator for feeding an inflating gas to the airbag are housed in a plate-shaped holding member arranged in front of the knees of a seated passenger. An airbag cover for covering the housed airbag and for allowing it to protrude when activated is mounted on the holding member. The holding member includes a bottomed box-shaped housing portion for housing the airbag and the inflator. The housing portion has a rear-facing opening. The airbag cover includes a door portion, a breakaway portion, a hinge portion, and a general portion. The door portion covers the opening of the housing portion for opening when pushed by the expanding airbag. The thinned breakaway portion is arranged at the periphery of the door portion and is broken for the door portion to open. The hinge portion is arranged at one side of the door portion for providing a pivot for the door portion to open. The general portion is arranged around the door portion with the breakaway portion and the hinge portion between them, for covering the periphery of the rear housing portion of the holding member. Mounting members to be mounted at the housing portion are arranged at a plurality of locations of the general portion, in the vicinity of the periphery of the opening of the housing portion.
In the knee protecting airbag device thus constructed, the airbag expands with the inflating gas discharged by the inflator. Then, the airbag pushes the door portion of the airbag cover and breaks the breakaway portion so that the door portion opens and pivots at the hinge portion. As a result, the airbag protrudes from the housing portion in the rearward direction and extends and expands greatly to protect the knees of the passenger.
In the knee protecting airbag device thus constructed, the airbag cover is mounted at a plurality of mounting members in the general portion, near the periphery of the housing portion opening, through the holding member. When the airbag expands, therefore, the breakaway portion and the hinge portion of the general portion, near the opening periphery of the housing portion, are hard to move relative to the housing portion. As a result, the pushing force of the airbag acts properly on the breakaway portion to break the breakaway portion smoothly. In addition, the hinge portion, which pivots when the door portion opens, is also hard to move relative to the housing portion and can stabilize the opening action of the door portion. Even if the airbag cover is made of a synthetic resin such as a thermoplastic elastomer, therefore, the door portion is smoothly opened when pushed by the airbag.
In the knee protecting airbag device thus constructed, therefore, the door portion can be smoothly opened by the pushing force of the airbag, even when the airbag cover, which has the integrated door portion, is mounted on the holding member in front of the knees of the seated passenger.
The individual mounting members of the airbag cover are only inserted in the holding member around the opening of the housing portion, so that the external surface area of the holding member is not reduced. Even if the knees of the passenger interfere with the holding member in an unexpanded state of the airbag, therefore, the holding member can engage the knees over a wide area. Accordingly, the holding member can support the front side of the airbag when the airbag has completed its expansion, so that the airbag is stably supported by the holding member when expanded.
In the knee protecting airbag device thus constructed, the airbag and the inflator are housed in the housing portion mounted on the holding member, and the airbag cover is mounted on the holding member. The airbag cover is provided with the door portion, for covering the folded airbag, and the general portion, for covering the rear side of the holding member at the periphery of the housing portion opening. In short, the airbag, the inflator, the airbag cover and the holding member can be assembled in advance. When the airbag, the inflator, the airbag cover and the holding member are assembled in advance, therefore, the airbag and its associated parts can be transported and stored in the assembled state. Therefore, it is easy to handle the individual members while they are mounted on the vehicle.
In the knee protecting airbag device thus constructed, moreover, it is preferred that the individual mounting members of the air bag cover have retaining holes. The housing portion has a plurality of hooks to be inserted into and retained by the retaining holes.
With the knee protecting airbag device being thus constructed, the work to mount the mounting members on the housing portion can be completed by inserting the individual hooks of the housing portion into the retaining holes of the individual mounting members of the airbag cover and by retaining the mounting members by the individual hooks. It is, therefore, possible to reduce the number of steps of and the cost of mounting the airbag cover on the holding member.
In the knee protecting airbag device thus constructed, it is preferred that the holding member comprises joining portions connected to the vehicle body, which are joined when the knee protecting airbag device is mounted on the vehicle. A kinetic energy absorbing member, which is capable of absorbing the kinetic energy of the knees, is arranged on the body of the vehicle at positions where the joining portions are connected.
With the knee protecting airbag device being thus constructed, the kinetic energy absorbing member is deformed in absorbing the kinetic energy of the knees if the expanded airbag fails to absorb the kinetic energy of the knees fully. Therefore, the knees of the passenger can be properly protected by lessening the impact on the knees.
Moreover, the third object of the invention can be achieved by a knee protecting airbag device having the following construction.
A knee protecting airbag device comprises an airbag module arranged in front of the knees of a seated passenger. The airbag module includes a knee protecting folded airbag, an inflator capable of feeding inflating gas the airbag, a case for housing the airbag and the inflator, and an airbag cover for covering the rear-facing opening of the case. The case has an opening for allowing the airbag to protrude toward the rear of the vehicle when it expands. The knee protecting airbag device further includes a plate-shaped holding member made of a deformable material. The holding member has a plate-shaped portion, extending around the opening of the case, and a mounting portion to be mounted on the vehicle body. The plate-shaped portion is arranged in front of the area occupied by the airbag when the airbag has completed its expansion. The mounting portion is arranged near the periphery of the plate-shaped portion. The holding member is constructed to hold the case that houses the airbag, the inflator, and the airbag cover. Then, when a kinetic energy higher than a predetermined level is applied by the knees to the airbag, the plate-shaped portion is deformed to absorb the kinetic energy of the knees.
With the knee protecting airbag device being thus constructed, the plate-shaped portion of the holding member is deformed to absorb the excess kinetic energy of the knees, if the airbag, after completely expanding, is flattened and the kinetic energy still has not been completely absorbed.
The plate-shaped portion of the holding member is extended from the periphery of the opening of the case such that it is arranged in front of the area occupied by the airbag when the airbag has completed its expansion. Therefore, the plate-shaped portion of the holding member can absorb the kinetic energy of the knees properly through the airbag when the airbag has completed its expansion.
Here, the plate-shaped portion of the holding member is extended from the periphery of the opening of the case such that it covers the area in front of the airbag when the airbag has completed its expansion. In this way, the plate-shaped portion is arranged in a large flat area in the vertical and transverse directions of the vehicle. Even with a small deformation stroke at the time of absorbing the kinetic energy, therefore, the kinetic energy of the knees can be sufficiently absorbed by the plate-shaped portion of the holding member.
The holding member is fixed to the vehicle body at mounting portions near the periphery of the plate-shaped portion so that the mounting portions will not obstruct the deformation of the plate-shaped portion.
The plate-shaped portion of the holding member does not extend in the longitudinal direction of the vehicle, as does the mounting bracket of the prior art. Specifically, the plate-shaped portion of the holding member is extended from the periphery of the opening of the case and arranged flatly in the vertical and transverse directions of the vehicle such that it is arranged in front of the area occupied by the airbag when the airbag has completed its expansion. Therefore, the airbag module can be easily arranged even if less space is available in front of the airbag module.
The mounting portion of the holding member need not be extended longitudinally from the periphery of the plate-shaped portion. If the airbag module can be mounted and fixed at a predetermined portion of the vehicle body, it can extend transversely from the periphery of the plate-shaped portion. In this case, the size of the airbag device in the longitudinal direction of the vehicle can be made shorter and more compact to improve the degree of freedom in finding a location for the airbag device.
In the knee protecting airbag device thus constructed, therefore, it is possible to absorb the kinetic energy of the knees, if such kinetic energy is not fully absorbed by the airbag, and to improve the degree of freedom in placing the airbag device.
In the knee protecting airbag device thus constructed, moreover, it is preferred that the plate-shaped portion of the holding member has ribs capable of adjusting the quantity of the kinetic energy of the knees that can be absorbed.
In the knee protecting airbag device thus constructed, it is preferred that the plate-shaped portion of the holding member has a flange portion arranged on its periphery for adjusting the quantity of the kinetic energy of the knees that can be absorbed.
As in the construction thus far described, ribs, which are for adjusting the absorption quantity of kinetic energy are arranged on the plate-shaped portion of the holding member, or a flange portion for adjusting the absorption quantity of kinetic energy is arranged on the periphery of the plate-shaped portion. Thus, the absorption quantity of kinetic energy can be easily adjusted to correspond to the deformation stroke or the like of the plate-shaped portion by setting the number, shape and arranged position of the rib and flange portions.
The fourth object of the invention can be achieved by a knee protecting airbag device having the following construction.
A knee protecting airbag device is arranged in front of the knees of a seated passenger. The knee protecting airbag device comprises a knee protecting folded airbag, an inflator for feeding inflating gas to the airbag, a case, which opens toward the rear of the vehicle for housing the airbag and the inflator, and an airbag cover for covering the case on its rear-facing side. The airbag cover is formed of an integral molding, including a door portion for covering the opening of the case and a general portion arranged around the door portion. The door portion includes a hinge portion, which is arranged at the lower edge, for providing a pivot when the door portion is opened, and a thinned breakaway portion, which is arranged at the periphery, other than the hinge portion. The door portion can be opened downward when the airbag expands. Extension promoting means for quickly opening the door portion to promote the extension and expansion of the airbag is arranged near the door portion.
With the knee protecting airbag device thus constructed, the door portion can be quickly opened by the extension promoting means at the beginning of the expansion of the airbag. As a result, the airbag can be quickly protruded to extend and expand from the opening of the quickly opened door portion. In the knee protecting airbag device thus constructed, the door portion is opened downward, with the opening being widest at the upper edge. In other words, the airbag can easily protrude upward from the opening portion of the upper end side of the door portion of the largest opening side. By the opening action of the door portion, therefore, the airbag can be guided upward. As a result, the airbag can extend and expand quickly upward.
In the knee protecting airbag device thus constructed, therefore, the airbag can be quickly extended to protect the knees of the passenger properly.
In the knee protecting airbag device thus constructed, the airbag cover is formed by an integral molding including the door portion, which has the breakaway periphery, and the general portion, which is around the door portion. Therefore, the door portion is not disharmonious with the surrounding general portion but provides an excellent design.
In the knee protecting airbag device thus constructed, it is preferred that the door portion is arranged at an inclination so that its upper edge is more toward the rear and its hinge portion is more toward the front.
In the knee protecting airbag device thus constructed, even if the upper edge of the door portion, the side that opens first, is arranged toward the rear of the vehicle and removed from the housed airbag and inflator, the extension promoting means is arranged near the door portion, so that the door portion can be quickly opened. Therefore, the airbag can quickly extend and expand. With the knee protecting airbag device being thus constructed, the lower side of the door portion in the airbag cover can be arranged toward the front so that the space in front of the knee, or the space near the lower portion of the passenger, can be kept wide. Therefore, the airbag device can be mounted on the vehicle without interfering with the toes or the like of the passenger.
In the knee protecting airbag device thus constructed, the case preferably includes a peripheral wall portion and a bottom wall portion. The airbag cover has mounting wall portions for mounting and fixing the airbag cover on the case peripheral wall portion. The mounting wall portions, which serve as the extension promoting means, are arranged near an upper end breakaway portion, which is arranged on the upper end of the door portion.
With the knee protecting airbag device thus constructed, the portion near the upper end breakaway portion is firmly connected to the case by the mounting wall portions, which serve as the extension promoting means. In other words, with the protrusion of the airbag, the portion near the upper end breakaway portion is not moved away from the case by the pushing force of the airbag. By the airbag, therefore, the upper end breakaway portion on the upper edge, where the opening of the door portion starts, can be smoothly broken so that the remaining breakaway portions can also be smoothly broken. As a result, the door portion can be quickly opened so that the airbag can quickly protrude to extend and expand from the opening of the opened door portion.
In the knee protecting airbag -device thus constructed, it is preferred that a guide wall portion for covering the lower area of the opening is arranged on the case near the door portion. The guide wall portion can serve as the extension promoting means to guide the expanding airbag toward the upper side of the door portion.
In case the knee protecting airbag device is thus constructed, the airbag, when fed with the inflating gas, is guided toward the upper side of the door portion by the guide wall portion, which serves as extension promoting means. At the beginning of the extension of the airbag, therefore, the breakaway portion, which is arranged on the upper edge of the door portion, can be broken to smoothly open the downward-opening door portion from the upper edge. As a result, the door portion can be quickly opened so that the airbag can quickly protrude from the opening formed by the opened door portion.
In the knee protecting airbag device thus constructed, it is possible that the door portion has ribs formed to protrude forward. The face of each forward-facing rib is a face to receive a pushing force and serves as the extension promoting means for opening the door portion when pushed by the airbag.
If the knee protecting airbag device is thus constructed, at the beginning of the expansion of the airbag, the protruding airbag pushes the front face of the rib backward to open the door portion. Usually, in the case of a knee protecting airbag device constructed with no rib on the door portion, the protruding airbag pushes the front face of the door portion to open the door portion. If the knee protecting airbag device is constructed with ribs, more specifically, the rib shortens the distance between the airbag and the door portion substantially. As compared with an airbag device having no rib, therefore, the door portion can be opened more quickly. As a result, the airbag can quickly protrude to extend and expand from the opening of the door portion, which is opened quickly.
In the knee protecting airbag device thus constructed, it is possible that the case includes a peripheral wall portion and a bottom wall portion. A left side wall portion and a right side wall portion, which are arranged transversely of the vehicle in the case peripheral wall portion, are inclined. The left side wall portion and the right side wall portion act as extension promoting means.
If the knee protecting airbag device is thus constructed, the inflating gas discharged from the inflator is guided upward in the airbag by the left side wall portion and the right side wall portion. In other words, the expanding airbag can be guided toward the upper side of the door portion. By the protruding airbag, therefore, the downward door portion can be smoothly opened from the upper end side. As a result, the airbag can be quickly protruded to extend and expand from the opening of the door portion.
Moreover, the fifth object of the invention can be achieved by a knee protecting airbag device having the following construction.
A knee protecting airbag device comprises a folded airbag, an inflator for feeding an inflating gas to the airbag, and a case housing the airbag and the inflator, and the device is arranged below a steering column. The airbag, when fed with the inflating gas, extends and expands while protruding rearward from the opening of the case, to protect the knees of the passenger. The case is opened toward the rear of the vehicle and includes a peripheral wall portion and a bottom wall portion, which closes the front side of the peripheral wall portion. The inflator is a cylinder-type inflator and is housed in the case such that its axis is generally parallel to the axis of the peripheral wall portion.
In the knee protecting airbag device thus constructed, the cylinder-type inflator is arranged such that its axis is generally parallel to the axis of the case peripheral wall portion. In addition, the axial dimension of the cylinder-type inflator is greater than the external diameter. If the inflator is arranged in the case such that its axis is generally parallel to the axis of the peripheral wall portion, therefore, the dimension, or width, perpendicular to the axis of the case may be set to the sum of the external diameter of the inflator and the size of the space that is required to house the folded airbag. As a result, the dimension, or width, perpendicular to the axis of the case can be made smaller than that of a case in which a cylinder-type inflator is arranged with its axis generally perpendicular to the axis of the case.
In the knee protecting airbag device thus constructed, therefore, the width of the case, which is perpendicular to its axis, can be reduced and thus the airbag device can be placed in a narrow housing space.
Moreover, it is possible that the inflator is a disc-type inflator and is mounted and fixed on the peripheral wall portion of the case such that its axis is generally perpendicular to the axis of the peripheral wall portion.
In the knee protecting airbag device thus constructed, the disc type inflator is mounted and fixed on the peripheral wall portion of the case such that its axis is generally perpendicular to the axis of the case peripheral wall portion. The external diameter of the disc-type inflator is larger than its axial dimension. If the inflator is mounted and fixed on the peripheral wall portion of the case so that its axis is generally perpendicular to the axis of the peripheral wall portion of the case, the distance from the wall portion on which the inflator is mounted to the wall portion confronting the inflator may be set to be the sum of the axial length of the inflator and the size of the space required to house the folded airbag. If the inflator is fixed on an upper or lower wall, for example, the vertical dimension, perpendicular to the axis of the case, can be reduced. If the inflator is fixed on a left or right wall, on the other hand, the transverse dimension, perpendicular to the axis of the case, can be reduced. As a result, the dimensions in the directions perpendicular to the axis of the case can be made smaller than those of a case in which the inflator is mounted and fixed on the bottom wall portion.
In the knee protecting airbag device thus constructed, therefore, the size of the case can be reduced in a direction perpendicular to the axis, and the device can be placed in a narrow housing space.
In the knee protecting airbag device thus constructed, the case is preferably constructed such that the upper end of the open face is positioned closer to the rear of the vehicle than the lower end of the open face. The inflator is mounted and fixed on the upper wall portion of the peripheral wall portion.
In the knee protecting airbag device thus constructed, the inflator is mounted and fixed on the upper wall in the case, and the upper edge of the opening face is positioned close to the vehicle rear. Moreover, the length of the upper wall portion of the case can be increased in the longitudinal direction to the extent that the rear edge is positioned rearward relative to that of the remaining peripheral wall portion of the case. Therefore, the depth of the case can be made smaller than that of a case in which the inflator is mounted and fixed on the remaining peripheral wall portion.
In addition, the inflator can be located outside of the case.
In the knee protecting airbag device thus constructed, the inflator is not located in the case, and only the folded airbag and the gas feed passage for feeding the inflating gas to the airbag are arranged in the case. Such a gas feed passage has a smaller volume than that of the inflator. Therefore, a dimension in a direction perpendicular to the axis of the case can be made smaller than that of the airbag device in which the inflator is located in the case.
Therefore, the knee protecting airbag device thus constructed can be placed in a narrow housing space.